Considerations for Setting Up a Constant Gamma Clutter Simulation
When you use constantGammaClutter, you must
configure the object for the situation you are simulating, and confirm that the
assumptions the software makes are valid for your system.Physical Configuration Properties
The constantGammaClutter object has
properties that correspond to physical aspects of the situation you are modeling.
These properties include:
Propagation speed, sample rate, and pulse repetition frequency of the signal
Operating frequency of the system
Altitude, speed, and direction of the radar platform
Depression angle of the broadside of the radar antenna arrayClutter-Related Properties
The object has properties that correspond to the clutter characteristics, location, and modeling fidelity. These properties include:
Gamma parameter that depends on the terrain type and system’s operating frequency.
Azimuth coverage and maximum range for the clutter simulation.
Azimuth span of each clutter patch. The software internally divides the
clutter ring into a series of adjacent, non-overlapping clutter
patches.
Clutter coherence time. This value indicates how frequently the software changes the set of random numbers in the clutter simulation.
In the simulation, you can use identical random numbers over a time interval or uncorrelated random numbers. Simulation behavior slightly differs from reality, where a moving platform produces clutter returns that are correlated with each other over small time intervals.Working with Samples or Pulses
The constantGammaClutter object has
properties that let you obtain results in a convenient format. Using the OutputFormat property, you can choose to have the
step method produce a signal that
represents:
A fixed number of pulses. You indicate the number of pulses using the NumPulses property of the object.
A fixed number of samples. You indicate the number of samples using the NumSamples property of the object. Typically, you use the number of samples in one pulse. In staggered PRF applications, you might find this option more convenient because the step output always has the same matrix size.Assumptions
The clutter simulation that constantGammaClutter provides is
based on these assumptions:
The radar system is monostatic.
The propagation is in free space.
The terrain is homogeneous.
The clutter patch is stationary during the coherence
time. Coherence time indicates how frequently
the software changes the set of random numbers in the clutter simulation.
Because the signal is narrowband, the spatial response and Doppler shift can be
approximated by phase shifts.
The radar system maintains a constant height during
simulation.
The radar system maintains a constant speed during
simulation.